The present invention relates to a motorized vehicle power system provided with a battery control unit for executing control of the state of a rechargeable battery of Nixe2x80x94Cd, Nixe2x80x94MH or the like to be used as an energy source for, for example, a motorized bicycle, a motorized wheelchair, a motorized S/C and a charging unit for electrically charging the rechargeable battery.
It is generally well known that the so-called xe2x80x9cmemory effectxe2x80x9d occurs in a rechargeable battery such as Nixe2x80x94Cd and Nixe2x80x94MH batteries that employ Ni for their positive electrodes. The memory effect results if charging is repeated without discharging the electric charges to a sufficient depth of discharge. This results in the voltage characteristic in the discharging stage being degraded with a reduction in discharge capacity to a discharge stop voltage. It is known that the battery can be effectively refreshed by being once discharged to the depth of discharge (refreshing discharge) by a discharger in order to cancel the memory effect. Recently, in view of economical wastefulness caused by the separate installation of a charger and a discharger, it has been proposed to provide a built-in discharger inside the charger and let the user select between a charging operation and a refreshing discharge operation manually by means by means of a switch or the like of the charger.
The refreshing discharge is a very effective means for canceling the memory effect. However, due to the existence of innate variation in capacity between the cells of an assembled battery constructed of a plurality of connected single cells, it is possible that one or more cells become overdischarged in the refreshing discharge stage. If the refreshing discharge is freely executed by the user""s decision, then a refreshing discharge may be executed although not required. This consequently leads to the problem that the frequency of refreshing discharge is increased and causes deterioration of the assembled battery.
The present invention has been made in view of the aforementioned problems and has the object of providing a motorized vehicle power system capable of optimizing the refreshing discharge timing of the rechargeable battery.
FIG. 14 is a schematic diagram showing the basic relationship of the components according to the first inventive aspect. As shown there a motorized vehicle power system 403 is provided with a rechargeable battery 400, a battery control unit 401 for executing control of battery conditions including the remaining capacity of the battery 400 and a charging unit 402 for charging the rechargeable battery 400. The charging unit 402 is provided with a discharging means 404 for executing refreshing discharge of the rechargeable battery 400. A discharge control means 405 controls the refreshing discharge executed by the charging means 404 on the basis of a refreshing discharge requirement signal sent from the battery control unit 401.
According to a second inventive aspect, based on the first inventive aspect, the discharge control means 405 of the charging unit 402 controls the discharging means 404 so as to enable refreshing discharge by the discharging means 404 only when a refreshing discharge requirement signal is received from the battery control unit 401.
According to a third inventive aspect, based on the second inventive aspect, the discharge control means 405 displays on a display means 407 the information of the reception of the refreshing discharge requirement signal from the battery control unit 401 upon receiving the signal.
According to a fourth inventive aspect, based on the third inventive aspect, the discharge control means 405 operates to execute refreshing discharge by the discharging means 404 when a refreshing switch 409 is turned on within a specified time and thereafter executes charging and operates to execute charging when the switch is not turned on while the information of the reception of the refreshing discharge requirement signal from the battery control unit 401 is displayed on the display means 407.
According to a fifth inventive aspect, based on the second inventive aspect, the discharge control means 405 operates to start the refreshing discharge by the discharging means 404 and display the refreshing in operation on the display means 407 upon receiving the refreshing discharge requirement signal and operate to stop the refreshing discharge and execute charging when a refresh cancel switch is turned on.
According to a sixth inventive aspect, based on any one of the first through fifth inventive aspects, the battery control unit 401 decides whether or not the refreshing discharge is necessary on the basis of at least any one of (a) the number of times of charging, (b) the number of times of discharging or (c) the number of cycles of charging and discharging, counted from the initial or preceding refreshing discharge.
According to a seventh inventive aspect, based on any one of the first through fifth inventive aspects, the battery control unit 401 decides that the refreshing discharge is necessary when a difference larger than a specified quantity exists between a battery effective capacity perceived by the battery control unit 401 and a discharge capacity down to a specified setting voltage.
According to an eighth inventive aspect, based on any one of the first through fifth inventive aspects, the battery control unit 401 decides that the refreshing discharge is necessary when the refreshing discharge is not executed down to the completion of refreshing after the display of the necessity of the preceding refreshing discharge.
According to a ninth inventive aspect, based on any one of the first through fifth inventive aspects, the battery control unit executes weighting of the number of times of charging on the basis of either a battery temperature at the time of starting charging or a battery temperature at the time of ending charging and decides that the refreshing discharge is necessary when the weighted number of times of charging becomes equal to or greater than a predetermined value.
According to a tenth inventive aspect, based on the ninth inventive aspect, the battery control unit increases the weighting as the battery temperature becomes higher.
According to an eleventh inventive aspect, based on the ninth or tenth inventive aspect, the battery control unit counts the number of times of charging when discharging is executed by a specified quantity or more after the end of the charging.
According to a twelfth inventive aspect, based on any one of the first through eleventh inventive aspects, a removable battery casing to be mounted on a vehicle and a charging unit 402 that is mounted on or not on the vehicle are provided. The removable battery casing has the battery control unit 401 built-in.
According to a thirteenth inventive aspect, based on any one of the first through eleventh inventive aspects, the rechargeable battery 400, the battery control unit 401 and the charging unit 402 are mounted in a fixed manner on the vehicle.